Dimming means for a lighting system

ABSTRACT

Lighting system has slave switch adapted to dim system when master switch is thrown off then on within short time interval. Throwing master switch on after short time interval expires instead restores system to full brightness.

United States Patent 1 Ackermann 51 Oct. 28, 1975 DIMMING MEANS FOR A LIGHTING SYSTEM [75] Inventor: Walter Thomas Ackermann,

Watertown, Conn.

[73] Assignees: Indevco Corporation, Watertown; Dallet Hoopes, Litchfield, both of Conn. part interest to each [22] Filed: Aug. 8, 1974 [21] App]. No.: 495,684

[52] US. Cl. 315/73; 315/64; 315/69;

315/90; 315/313; 315/360; 337/123; 337/136 [51] Int. Cl. HOIK 1/64; HOIK 9/08 [58] Field of Search 315/50, 64, 65, 67, 69,

315/73, 74, 75, 90, 125, 127, 128, 193, 313, 315/360, DIG. 4; 337/123, 125-128, 337/130, 131, 136 [56] References Cited UNITED STATES PATENTS 5/1930 De Castro 315/65 2,308,522 1/1943 Leuthold 337/125 2,333,125 11/1943 Schmidinger.. 337/136 3,218,411 11/1965 Siiberg 337/125 X 3,227,920 1/1966 Peek, Jr. et al.... 315/66 3,234,342 2/1966 Murray 315/65 X Primary ExaminerJames W. Lawrence Assistant ExaminerE. R. LaRoche Attorney, Agent, or Firm-Dallett Hoopes [5 7] ABSTRACT Lighting system has slave switch adapted to dim system when master switch is thrown off then on within short time interval. Throwing master switch on after short time interval expires instead restores system to full brightness.

13 Claims, 21 Drawing Figures US. Patent" Oct. 28, 1975 Sheet 1 of4 3,916,249

2 I id .II M u m I... lv kt a I q US. Patent Oct.28, 1975 Sheet20f 4 3,916,249

US. Patent @128, 1975 Sheet3 01*4 3,916,249

Pm zoom US. Patent Oct. 28, 1975 Sheet 4 of 4 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a dimming means for a lighting system. More specifically, the invention relates to means by which an incandescent light bulb can be' dimmed by the intentional interruption of the power supply for a short time period. The invention makes the light dimmable even though it is disposed in a conventional socket in a conventional two-wire circuit. The invention also has application to other types of lighting systems including fluorescent systems; however, the preferred embodiment of the invention is with an in-- candescent light bulb.

2. Description of the Prior Art In the prior art, there are showings of various devices by which a light may be dimmed either by the socket switch itself, or by some remote switching device. Probably the best known dimming means for a lighting system involves the conventional three-way bulb in which an incandescent bulb is equipped with a pair of filaments with ends having a common contact, for instance, the center contact of the bulb base, and having separate contacts for the two remaining ends of the respective filaments; for instance, the brass screw base itself, and an auxiliary contact located somewhere between the center contact and the screw base. In operation, such a three-way bulb is inserted into a special socket having a switch with four positions: off, energizing one of the filaments, energizing the other of the filaments, and finally, energizing both filaments. Such arrangements thus require not only the special twofilament bulb but also the special light bulb socket with the indicated four-position switch.

Another dimming means for a lighting system is the so-called dimmer switch which is substituted in the wall switch box for the conventional switch. The dimmer switch will take one of two forms; a high-low-off type switch wherein a diode rectifier is disposed across the switch contacts in the intermediate or dimmed position; and an infinitely variable rheostat-like control generally of the type including SRC rectifier means wherein by turning the dial the amount of power passing through the switch is regulated in a way well known in the art. In either case, the dimmer switch involves the expense of a special switch and the installation of the switch, usually by a licensed electrician.

SUMMARY OF THE INVENTION Under the present invention, there is provided means by which a standard lamp socket and power supply may be used to establish a dimmed condition for a lighting system. The means under the invention invariably involves a switch provided preferably in the light bulb itself or a special wafer inserted in the light bulb socket between the central contact of the socket and the central contact of the screw bulb base. In either case, the means embodying the invention is actuated by an interruption of the power supply for a brief period no greater than a preset period (for instance, 3 seconds). The interruption of the power supply may be accomplished, then, by flicking the wall switch or the socket switch for the bulb off and then on.

More specifically and yet still briefly. the dimming means herein may comprise a special switch either in the bulb or in the wafer described above or in a bulbreceiving adaptor. For convenience and clarity herein, this switch is referred to as the slave switch, while the wall or socket or other circuit controlling switch is referred to as the master switch. The slave switch includes a resistive wire adapted to carry the current to the light bulb. The wire lengthens as it heats when current passes through it and shortens when the current is interrupted. This change in dimension manipulates the slave switch parts. Thus, turning the master switch on immediately after an interruption maintains the wire at intermediate length at which the bulb is dimmed. Keeping the master switch off for longer than the preset period shortens the wire further and turns the slave switch on so that when the master switch is reactivated, the bulb will light at full brightness.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and objects of the invention will be clear from a reading of the following specifiction and examination of the attached drawings, all of which show structure embodying the invention. In the drawmgs:

FIG. 1 is a perspective view of an incandescent light bulb embodying the invention and having part of its glass envelope removed;

FIGS. 2 through 5 show various conditions of the slave switch disposed in the glass envelope in the FIG. 1 embodiment, the views being enlarged sectional views taken on the line 2-2 of FIG. 6;

FIG. 6 is an enlarged view of the slave switch in a position rotated about its longitudinal axis from that shown in FIG. 1;

FIG. 7 is an exploded view of structure comparable to that shown in the assembled view (FIG. 6);

FIG. 8 is an enlarged sectional view taken on the line 88 of FIG. 6.

FIG. 9 is an enlarged sectional view taken on the line 9-9 of FIG. 6.

FIG. 10 is an enlarged sectional view taken on the line FIG. 11 is an enlarged sectional view taken on the line 11-11 of FIG. 6;

FIG. 12 is a schematic view showing the electrical environment of the slave switch of FIGS. 1 through 11;

FIG. 13 is a fragmentary sectional view showing a slave switch device embodying the invention disposed in a wafer located in a conventional lamp socket;

FIG. 14 is a sectional view taken on the line 14-14 of FIG. 13; 1 f

FIG. 15 is a greatly enlarged view of the wafer with its top cover removed;

FIG. 16 is a sectional view taken on the line 16-16 of FIG. 15;

FIGS. 17 through 19 are schematic views showing in diagrammatic form the movement of the parts in the FIGS. 13 through 16 embodiment;

FIG. 20 is a schematic view showing the disposition of the various elements in the circuit embodying the FIGS. 13 through 16 embodiment; and

FIG. 21 is a perspective exploded view of a wafer embodying the invention on a scale comparable to that of FIGS. 15 and 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more specifically to the drawings, a light bulb embodying the invention is generally designated in FIG. 1. It comprises a screw base 12 and a center contact 14. As is conventional, a glass envelope 16 is supported on the screw base and a glass stem 18 within the envelope 16 holds the internal structure including filaments F1 a'ndF2.

Embedded in and extending up from the stem 18 are the more or less parallel filament supports 20 and 22 which are connected at the lower ends by well known means to a common terminal, for instance, the central contact 14. A third support 24 electrically engages the opposite end of the filamentFl, the lower end of the support being embedded in the glass stem 18 but not electrically connected to any part of the external contact.'Astub support26 extends upward through the glass stem 18 and is connected at its lower end to the screw base 1 2. Y

The slave switch, best seen in FIG. 6, generally designated 28, comprises a base 30 which includes a vertically disposed channel-like member 32 (FIG. 7) including a web 34 and a pair of side flanges 36 and 38. As shown in FIG. 7, the channel-like member 32 has adjacent its lower end outwardly an extending foot 40 which is coplanar with the web 34. Above and below the foot 40 are tabs 42 in the same plane with the flange 36, and similar tabs 44 aligned with the tabs 42 extending out beyondthe flange 38 on the opposite side of member 32. A cut-out 45 is disposed between. the tabs 44. The base 30 may be a brass stamping.

Adjacent the upper end of the base 30, the flanges 36 38 are formed with outwardly directed nibs 46. A rigid arm 48 is disposed above the base and comprises a U-shaped element havingg parallel arms 50 and a transverse bight 52. As shown in FIG. 7, adjacent their lower ends the arms are formed with openings 54 which are aligned, and in assembly engage the nibs 46 in a snug compressive fit due to the resilience of the arms 50. This provides a somewhat stiff pivoting relationship between the base 30 and the rigid arm 48.

Extending downward and intergral with the bight 52 istheear 54. The ear is apertured as at 56 and receives the central hub 58 of a contact 60 which hub 58 is. thereafter peened over to in effect form a rivet, pres' enting the head of the contact 60 inward. The legs 50 are formed with inwardly struck fingers 62. The right arm 48 is likewiseformed from a brass stamping and the contact 50 may be of titanium ,or steel alloy, as is conventional in contacts. An insulationshoe 64 is provided and is of generally channel shape including the web 66 and the flanges 68 and 70. The flange 70 has a cut-out 72 intermediate its ends. I V i A resilient arm 74 is formed of stip brass or other resilient conductive material and comprises an elongated strip 76 normally bent or biased, as shown in FIG. 3 and perpendicular shelves 80 and 82 areformed at the upper and lower ends respectively. Each of the shelves is apertured as at 82 and 84 respec t'ivelyfthe aperture 84 being somewhat larger than the aperture 83. A second contact 86, identical to contact 60, has a hub 88 which is received into an opening 90 and riveted therein as with contact 60. An insulating pad 77 is bonded onto the inside face of the arm 74 intermediate the ends. I

Completing the slave switch assembly, a length of resistive wire 92, preferably of Nichrome, is provided and a glass bead 94 is secured thereon adjacent the lower end although a tail 96 extends onward. Nichro'me is a trademark for a nickel-based resistive metal containing chromium and iron.

In assembly, as shown best in FIGS. 6 and 2, for instance, the rigid arm 48 is pivotally attached as described above, to the base 30. The shoe 64 is nested into the channel-shaped member 32 so that its web 66 engages the web 34 and the cut-out 72 of the shoe is aligned with the cut-out 45 of the base member. The resilient arm 74 is then manipulated so that the contact 86 opposes the contact 60 of the rigid arm 48 and the projection 78 extends through the cut-out 45. The insulating shoe 64 is, in this process, aligned with the fingers,62. The tabs 42 and 44 are then closed. nward tightly embracing the lower of the resilient arm 74 with the insulating shoe 64 therebetween so that the units are electrically insulated.

Finally, the length of wire 92 is threaded upward through the aperture 84 in the shelf 82 and through the aperture 83in the shelf and secured thereat in a mechanical and electrical connection. The bead is at a fixed location on the wire and serves to insulate the wire from the shelf 82, the hole 84 amply passing the wire, but not the bead.

, The resilient arm'74 is, as stated, of brass strip and is formed with a bias so that its upper end extends left- I wardly, as best shown in FIG. 3. For simplicity in FIG. 7, the arm 74 is shown as straight. In thesecuring of the wire 92 in final assembly and when thewire is cold, the wire places a rightward stress on the upper end of the resilient arm straightening out the arm as shown in FIG. 2 in much the same way as a bow string changes the shape of an archers bow. Y

The above-described assembly is" supported in the light bulb, as shown in FIG. 1. The foot 40.is secured adjacent the lower end to the filament support 24 as by welding or the like fully support theassembly 28. The projection 78, extending almost opposite the foot 40, supports the final filament suport 98 which extends upwardly from the projection 78 but not downwardly. Finally, the tail 96 ofwire 92 is electically and mechanically secured to the stub support 26 It can be seen that the stub support 26 does not extend upward far enough to touch either the projection 78 or the support 98 and thus the two are electrically isolated in the absence of other means.

With the above-described structure, the operation will be apparent from FIGS. 2 through 5. FIG. 2 shows the slave switch 28 in its normal position when the light bulb has been off for sometime and is literally cold; i.e., at room temperature. In this position, the wire 92 holds the resilient arm 74 practically vertical, as shown, with the pad 77 holding the rigid arm 48 rightwardly such that the contacts 60 and 86 engage. Thus, on closing the master switch, electicity flows from the screw base 12 up the stub support 26, toiftthe wire 92, to the arm 74, through contacts 86 and 60, through the arm 48, the base 30, out the shoe 40, up support 24 to filament Fl, down support 22 to the central contact 14.

86 urges, by its engagement with the contact 60, the rigid arm 48 to a leftward position dueto the natural bias of the resilient arm 74. During this time and therafter, while the master switch continues on, both filaments F1 and F2 are activated.

If now the master switch is flicked off, the wire 92 cools (FIG. 4), shortening and causing the contact 86 to pull away from contact 60, the arm 48 remaining in its leftward position. If at this movement the master switch is flicked on again, only filament F2 will light. Thiscondition will remain static as long as the master switch remains on because the current flowing through the Nichrome wire 92 is reduced as compared to its condition when both filaments are on, and this reduced flow is sufficient to maintain the length of the Nichrome wire so that the arm 74 remains in the positionshown in FIG. 4 and the contacts 60 and 86 stay open.

If now the master switch is thrown off and remains off for a period of time exceeding a pre-established period of time, for instance, three seconds, the wire 92 will cool sufficiently to draw the arm 74 rightward (FIG. 5) so that the pad 77 engages fingers 62 to mechanically pivot the rigid arm 48 rightwardly about the nibs 46. The pad 77 and the fingers 62 thus comprise a lostmotion device, the arm 74 thereby moving the arm 48 only after the arm 74 itself has moved rightward some distance. Because of the location of the finger 62 close to the pivot 46, and the distance of the contacts 60 far away therefrom, the mechanical advantage of this arrangement causes the movement of the upper portion of the rigid arm 48 back over a greater distance than that traversed by the pad 77 in the process so that the contacts 60, 86 are brought into re-engagement. Thereafter, i.e., after the wire 92 is cooled, it is in the condition of FIG. 2 so that future closing of the master switch causes the activation of both filaments F1 and F2.

It will thus be seen that the embodiments described in connection with FIGS. 1 through 12 make possible, using a conventional lighting circuit and a conventional bulb socket, means by which the light may be remotely dimmable by the master switch in the circuit. Clearly, the structure of slave switch 28 may be disposed outside of a conventional three-way bulb with appropriate alternations to the circuit shown in FIG. 12. However, the preferred use of the assembly is inside the glass envelope of an incandescent light bulb, as shown.

FURTHER EMBODIMENT An embodiment of the invention which may be readily disposed in a wafer is represented in FIGS. 13 through 21. Referring to FIG. 13, a wafter embodying the invention is generally designated 110. As shown, it may be disposed in the socket S between the central contact CS of the socket and the central contact CB of the lamp base. The thinness of the wafer 110 permits the screw base of the bulb B to be partly screwed in.

As viewed in FIG. 15, the wafer comprises a generally disc-shaped body 112 of hard insulating material, preferably plastic. It is superposed by an insulating cover 114 which is coextensive with the body 112 and has a central aperture 116 over which fits the cap terminal 118 of metal. The body 112 is formed with a recess 120 of generally rectangular shape but having a side-wise enlargement as at 122, as shown. Centrally of the wafer, the body is provided with an opening 124, preferably of the same size as the opening 116. In the opening is mounted the metal terminal cap 126, preferably identical with cap 118. Cap 126 is formed with openings 126a and 126b (FIG. 21) to receive wires of other elements (132, 146) in soldered connection. In the wafer is the slave switch generally designated 128.

Threadedly disposed in a suitable tapped bore 129 intersecting the recess and extending from the outside of the wafer is a contact screw 130. Preferably, the slot of the screw is accessible through the bore 129 from the outside to adjust the position of the screw. A wire 132 electrically connects the cap 126 and the screw so that the end of the screw becomes an electrical contact surface. A second screw 134 is provided in a second tapped bore 136 and its slot also is accessible from the outside of the wafer for adjustment purposes. Preferably, as shown, the screw 134 may be on a diameter of the wafer. The bore 136, as shown, intersects recess 120. It is desirable that the screws 130 and 134 be in the same plane, a plane parallel to the surfaces of the wafer and preferably bisecting the wafer.

As shown in FIG. 15, a slot 138 is formed across the wafer intersecting the recess 120. In the slot is snugly disposed a base plate 140. As shown in FIG. 15, the plate is apertured as at 142 and 144. Aside from the base plate 140, the base means includes an upwardly H-shaped spring 145 (FIG. 21) strip of brass which rests on the conductive plate 140. A diode rectifier 146 is electrically connected between the cap 126 and the base plate 140. A conductive element comprises a metal beam 148 which is rounded at its ends, as shown, and comprises (FIG. 16) a medical web 150 and the side flanges 152 and 154. A contact disc 156 is mounted at the side of the beam 148 and is electrically integral therewith (FIG. 21).

In the embodiment of FIGS. 13 through 21, the resistive wire 158 is provided with a glass bead 160 intermediate its major length and the tail 162. In assembly, the wire, which may be Nichrome wire, is threaded up through the opening 142 until the bead abuts the margin of the opening. The wire extends straight upward in a run 158a between the sides of the l-I-shaped spring 145 between the flanges of the l-beam and is secured at the top of the I-beam as at 164. The securement is not only mechanical but also electrical. The wire then extends in a run 158b down between the flanges 152, 154 on the other side of the medial web 150 and between the sides of the H-shaped spring 145 and passes through the aperture 144 and the base plate 140 and is there secured. It should be understood that current does not flow through the return section of the wire 158b. The return section is instead means to stabilize the beam and hold it down.

The cover 114 of the wafer may be held on the wafer by the rivets 166.

The tail 162 of the wire 158 may double back through the bead 160 and opening 142 without contacting the base 140 and extend upward and is electrically and mechanically secured to the upper cap 118 by being inserted into hole 118a provided in cap 118 and being soldered in place.

FIGS. 17 through 19 diagrammatically indicate the operation of the version of the slave switch disposed in the wafer 110. FIG. 17 shows the slave switch in the cold condition, that is, a condition in which the bulb B has not been activated for a relatively long period of time. It will be seen that the contact 130 is in engagement with the contact 156 on the beam 148. When the master switch M is thrown on, current passes from the center contact CS through the upward stretch of the wire 158a, down through the beam 148 to the contact 156, through the screw 130 and to the bulb B activating it at brightest intensity.

Subsequently, FIG. 18, the Nichrome wire 158 lengthens. This permits the top of the beam to move leftwardly pivotally about the inward end of the screw 130, the downward run of the wire 158a remaining constant and supplying a downward force vector reflecting the upward urging of l-I-shaped spring 145 which keeps both stretches of the wire 158 taut. The lower end of the beam moves rightward on spring 145.

Subsequently (FIG. 19), if the circuit is interrupted as by the opening of the master switch, the upward run of the wire 158a shortens causing the top of the beam 148 to move rightwardly resulting in the clockwise pivoting of the beam 148 about its engagement point with the spring 145. This causes the disengagement of the contact 156 from the screw 130 causing current now to flow to the lamp from the beam 148 through the H- shaped spring 145 to the base plate 140 and through diode rectifier 146 if the master switch is then closed within. a present period. This causes half power to flow to the filament of the bulb B resulting in a lighting of the bulb. Because the average current drawn is less than with the bulb on full, the power flowing through the upward stretch of the wire 158a is sufficient to maintain the length'of the wire constant so that the arrangement diagrammatically shown in FIG. 19 holds as long as the current remains on and the bulb remains on dim.

If, rather than closing the master switch in the interval in which the contact 156 does not engage the screw 120, but the upward stretch 15811 of the wire 158 is permitted to cool further, said stretch shortens causing the entire beam 148 to pivot about the screw 134. As this happens, the lower end of the beam 148 slides leftwardly (FIG. 19) along the arched spring 145 until the contact 156 engages the screw 130. This re-establishes the condition shown in FIG. 17 wherein if the master switch is subsequently closed, the bulb will come on, current passing the contact 156 to the screw 130 to short out the diode rectifier 146.

FIG. 20 demonstrates how the wafer with slave switch S disposed in the lamp socket fits into the circuit to bring about a dimming action when the master switch M is manipulated as described.

It will be understood that in the embodiment of FIGS. 13 through 21, dimming is achieved only by restoring within a preestablished period the master switch to closed position after it has been opened. The period may be, for instance, three seconds. Preferably, this is achieved by flicking off and immediately on the master switch M.

One of the features of the version of the slave switch disclosed in FIGS. 13 through 21 is that it is temperature compensated. Should the temperature of the environment change therefore, there will be no adverse effect on the operation of the switch. This is because the wire 158 extends on either side of the beam 148 and determines its attitude. As the ambient rises, there will be equal elongation on both stretches 158a and 158C, for instance, causing no change in the disposition of the beam with respect to the base 140. The spring 145 will compensate for the elongation of the stretches and keep those wires taut by raising the beam. Conversely; upon cooling of the environment, the stretches 1580 and 158b, being of the same material, will'both contract together so that the attitude of the beam 148 will not change. Spring yields downward as necessary during the contraction.

'An interesting feature of the structures disclosed herein is that the contacts 60, 86 and 130, 156 are closed and opened during the period in which the master switch is off so that there is no arcing problem connected with the making and breaking of the contacts.

It should be understood that herein the two versions of the slave switch disclosed are illustrative just as their respective mounting in the bulb and in the wafer are illustrative. Thus, the FIGS. l-12 version could be mounted in a wafer and the FIGS. l321 version could be in a bulb. The specific disclosures are illustrative not only as different slave switches possible, but also as different ways in which the switches may be employed in a lighting system. The word word herein and in the claims is intended to have a broad meaning including any electric means by which light is produced such as: a single incandescent electric bulb, an electric bulb having a plurality of filaments, a plurality of incandescent bulbs, and a plurality of fluorescent tubes.

It should thus be clear that the benefits of the above described embodiments will flow from other embodiments not described and hence the scope of the invention should not be limited by the embodiments herein disclosed, but should be limited by the following claim language and reasonable equivalents thereof:

I claim: I t

l. A system comprising an electic light-producing means, conducting means connecting the lightproducing means to a source of electric power, and switch means in the conducting means, the switch means being driven by a resistive wire element in series with the light-producing means, said switch means automatically dimming the light-producing means when the source of power is restored within an established time interval after the source of power has been interrupted, but not dimming the light-producing means if the source of power is restored after said preestablished interval is over.

2. A lighting system comprising at least two filament means disposed in evacuated environment means, conducting means connecting both filament means to a source of electric power, and switch means intermediate the conducting means for one of the filament means, the switch means being driven by a resistive wire element in series with the two filament means, the switch means deactivating the said one filament means when the source of power is restored within a preestablished time interval after it has been interrupted, but not deactivating said one filament means if the source of power is restored after said pre-established interval.

3. A lighting system as claimed in claim 2 wherein the environment means comprises a glass envelope and wherein the two filament means and the switch means are disposed in said envelope.

4. An incandescent light bulb comprising a glass envelope, a pair of filaments supported in the envelope, a base on the envelope having a pair of terminal means, conductive means operatively connecting the filaments in parallel to the terminal means, switch means connected between one side of one of the filaments and the conductive means, the switch means being driven by a resistive wire element in series with the filaments, the switch means disconnecting the said one filament if the power to the bulb is interrupted for a period of time greater than a first preset time and less than a second present time. I

S. A dimmable lighting system comprising: a. a filament means; b. a master switcch; V c. a slave switch comprising base means, a pair of cooperant switch contacts, means to move the contactsrelatively including a movable element mounting one of the contacts, and resistive wire means having one end mounted on the base means and the other end engaging the movable element,

the resistive wire means being electically in series with'the filament means; and

d. circuit means connecting the switches and filament means adapted when the contacts are closed to light the lighting system brightly and when the contacts are open to light the system dimly whereby when the master switch is opened, the resistive wire cools and contracts and the movable element moves, moving the contacts apart and then, after a delay, together again, and if the master switch is closed during the delay, the system lights dimly, the load of the dimly lit system being sufficient to maintain the length of resistive wire contact to keep the contacts apart.

6. A lighting system as described in claim wherein the slave switch is disposed in a wafer-like disc adapted to be inserted in the socket of a light bulb.

7. A light-dimming apparatus adapted to control the brightness of the filament means of an incandescent light bulb including:

a. a switch comprising:

1. base means;

2. a conductive element supported on the base means extending up from the base means and having an unsupported upper end, the upper end being predisposed to a first position toward one side of the switch from the element;

3. a resistive wire engaging at its upper end the upper end of the element and secured at its lower end to the base means at a point toward the other side of the switch from the element, the wire being taut and insulated from the base and the element except at a-second point adjacent the upper end of the element, the wire holding the element in a second position with its upper end toward the said other side of the switch when the wire is cold and adapted on passage of current to lengthen and permit the upper end of the element to move to the first position;

4. a pair of contacts, one contact being mounted on said one side of the switch from the element, the other contact being mounted on the element confronting and aligned with the one contact, and electrically connected to the resistive wire at the second point;

5. means for moving the relative position of the contacts using the change in length of the resistive wire so that the contacts are normally engaged but are disengaged as the wire shortens in cooling after the power supply to the switch is interrupted, and re-engaged after the interruption is more than a pre-established period; and

b. load means operatively connected to the switch and including the resistance of the full filament means when the contacts are closed and a greater resistance when the contacts are open,

whereby when the current is re-established prior to the end of the pre-established period, the load means draws enough current to maintain the length of the resistive wire such that the contacts remain disengaged, and whereby the filament means is dimmed when the contacts are disengaged.

8. A switch as claimed in claim 7 wherein the element is a rigid beam, the base means includes an arched metal stip convex upwardly and supports the bottom of the element keeping the wire taut and the means for moving include a fixed pivot pin mounted on said other side of the switch intermediate the ends of the element and said one contact is below the pivot pin, whereby when the resistive wire lengthens and the element inclines toward said one side, the contacts form a pivot point and the base of the element slides toward the said other side, and whereby when the current is interrupted, the wire contracts and pulls the top of the element toward the other side disengaging the contacts and subsequently, if the interruption continues, causes the element to engage the pivot pin, forcing the lower end toward the said one side and finally causing the contacts to re-engage.

9. A switch as claimed in claim 8, wherein the switch is disposed in a wafer-like disc adapted to be inserted in the socket of a light bulb, the load means includes a diode disposed electrically between the base means and the one contact, and terminal means are disposed centrally of the disc on the top and bottom thereof, one of the terminals being electrically connected to the one contact and the other to the resistive wire adjacent the base means.

10. A switch as claimed in claim 7 wherein the element is a resilient arm anchored at the base means and said one contact is disposed on a rigid arm pivoted above the base means and the means for moving comprises lost motion means adapted to pull the rigid arm back toward said other side of the switch after the resilient arm moves back a distance so that the contacts reengage.

11. A switch adapted to control one filament of a two-filament incandescent light bulb, the condition of the switch being responsive to the length of duration of interruption of current flow through the bulb and switch, the switch comprising:

a. base means;

b. a conductive resilient arm secured to and extending up from the base means and having a free upper end, the upper end being predisposed to a first position toward one side of the switch;

c. a resistance wire secured at its upper end to the upper end of the resilient arm and at its lower end to the base means at a point toward the other side of the switch from the arm, the wire being taut and insulated from the arm except at its securement to the arm, the wire holding the resilient arm in a second position with its upper end toward the said other side of the switch when the wire is cold and adapted on passage of current to lengthen and permit the upper end of the arm to move to the first position;

d. a conductive rigid arm insulated from the resilient arm, the rigid arm being pivotally attached to the base means at a point spaced above the securement of the resilient arm to the base means and extend- 1 1 ing upward alongside the resilient arm on the side opposite the resistance wire, the rigid arm being adapted to move in the samedirection as the resilient arm; v

e. contact means electrically integral with and mounted on the arms respectively at a level adjacent their upper ends, the contact means being closed when the resilient arm is in the first and the second positions;

f. lost-motion means associated with the two arms and spaced down from the contact means toward the pivot and adapted to permit the resilient arm to move freely away from the first position toward the second position and then to move the rigid arm with the resilient arm so that the contacts separate as the resilient arm leaves the first position and reengage as the resilient arm closely approaches the second position as the wire cools after the current is interrupted; and

g. means electrically connecting one side of a power supply to the lower end of the resistive wire, said one filament to the rigid arm, the said other filament to the resilient arm, and the other side of the power supply directly to the filaments,

whereby the resistance of the other filament by itself is sufficient load to maintain the resistive wire at a length when the contacts are disengaged such that the contacts remain disengaged.

12. A switch as claimed in claim 11 wherein the lost motion means comprise an insulating layer on the resilient arm and finger means aligned with the layer and disposed on the rigid arm on the said other side of the switch from the layer.

13. A switch as claimed in claim 11 wherein the switch is disposed inside the glass envelope of an incandescent light bulb. 

1. A system comprising an electic light-producing means, conducting means connecting the light-producing means to a source of electric power, and switch means in the conducting means, the switch means being driven by a resistive wire element in series with the light-producing means, said switch means automatically dimming the light-producing means when the source of power is restored within an established time interval after the source of power has been interrupted, but not dimming the light-producing means if the source of power is restored after said preestablished interval is over.
 2. A lighting system comprising at least two filament means disposed in evacuated environment means, conducting means connecting both filament means to a source of electric power, and switch means intermediate the conducting means for one of the filament means, the switch means being driven by a resistive wire element in series with the two filament means, the switch means deactivating the said one filament means when the source of power is restored within a pre-established time interval after it has been interrupted, but not deactivating said one filament means if the source of power is restored after said pre-established interval.
 2. a conductive element supported on the base means extending up from the base means and having an unsupported upper end, the upper end being predisposed to a first position toward one side of the switch from the element;
 3. a resistive wire engaging at its upper end the upper end of the element and secured at its lower end to the base means at a point toward the other side of the switch from the element, the wire being taut and insulated from the base and the element except at a second point adjacent the upper end of the element, the wire holding the element in a second position with its upper end toward the said other side of the switch when the wire is cold and adapted on passage of current to lengthen and permit the upper end of the element to move to the first position;
 3. A lighting system as claimed in claim 2 wherein the environment means comprises a glass envelope and wherein the two filament means and the switch means are disposed in said envelope.
 4. An incandescent light bulb comprising a glass envelope, a pair of filaments supported in the envelope, a base on the envelope having a pair of terminal means, conductive means opeRatively connecting the filaments in parallel to the terminal means, switch means connected between one side of one of the filaments and the conductive means, the switch means being driven by a resistive wire element in series with the filaments, the switch means disconnecting the said one filament if the power to the bulb is interrupted for a period of time greater than a first preset time and less than a second preset time.
 4. a pair of contacts, one contact being mounted on said one side of the switch from the element, the other contact being mounted on the element confronting and aligned with the one contact, and electrically connected to the resistive wire at the second point;
 5. means for moving the relative position of the contacts using the change in length of the resistive wire so that the contacts are normally engaged but are disengaged as the wire shortens in cooling after the power supply to the switch is interrupted, and re-engaged after the interruption is more than a pre-established period; and b. load means operatively connected to the switch and including the resistance of the full filament means when the contacts are closed and a greater resistance when the contacts are open, whereby when the current is re-established prior to the end of the pre-established period, the load means draws enough current to maintain the length of the resistive wire such that the contacts remain disengaged, and whereby the filament means is dimmed when the contacts are disengaged.
 5. A dimmable lighting system comprising: a. a filament means; b. a master switch; c. a slave switch comprising base means, a pair of cooperant switch contacts, means to move the contacts relatively including a movable element mounting one of the contacts, and resistive wire means having one end mounted on the base means and the other end engaging the movable element, the resistive wire means being electrically in series with the filament means; and d. circuit means connecting the switches and filament means adapted when the contacts are closed to light the lighting system brightly and when the contacts are open to light the system dimly whereby when the master switch is opened, the resistive wire cools and contracts and the movable element moves, moving the contacts apart and then, after a delay, together again, and if the master switch is closed during the delay, the system lights dimly, the load of the dimly lit system being sufficient to maintain the length of resistive wire contact to keep the contacts apart.
 6. A lighting system as described in claim 5 wherein the slave switch is disposed in a wafer-like disc adapted to be inserted in the socket of a light bulb.
 7. A light-dimming apparatus adapted to control the brightness of the filament means of an incandescent light bulb including: a. a switch comprising:
 8. A switch as claimed in claim 7 wherein the element is a rigid beam, the base means includes an arched metal stip convex upwardly and supports the bottom of the element keeping the wire taut and the means for moving include a fixed pivot pin mounted on said other side of the switch inteRmediate the ends of the element and said one contact is below the pivot pin, whereby when the resistive wire lengthens and the element inclines toward said one side, the contacts form a pivot point and the base of the element slides toward the said other side, and whereby when the current is interrupted, the wire contracts and pulls the top of the element toward the other side disengaging the contacts and subsequently, if the interruption continues, causes the element to engage the pivot pin, forcing the lower end toward the said one side and finally causing the contacts to re-engage.
 9. A switch as claimed in claim 8, wherein the switch is disposed in a wafer-like disc adapted to be inserted in the socket of a light bulb, the load means includes a diode disposed electrically between the base means and the one contact, and terminal means are disposed centrally of the disc on the top and bottom thereof, one of the terminals being electrically connected to the one contact and the other to the resistive wire adjacent the base means.
 10. A switch as claimed in claim 7 wherein the element is a resilient arm anchored at the base means and said one contact is disposed on a rigid arm pivoted above the base means and the means for moving comprises lost motion means adapted to pull the rigid arm back toward said other side of the switch after the resilient arm moves back a distance so that the contacts re-engage.
 11. A switch adapted to control one filament of a two-filament incandescent light bulb, the condition of the switch being responsive to the length of duration of interruption of current flow through the bulb and switch, the switch comprising: a. base means; b. a conductive resilient arm secured to and extending up from the base means and having a free upper end, the upper end being predisposed to a first position toward one side of the switch; c. a resistance wire secured at its upper end to the upper end of the resilient arm and at its lower end to the base means at a point toward the other side of the switch from the arm, the wire being taut and insulated from the arm except at its securement to the arm, the wire holding the resilient arm in a second position with its upper end toward the said other side of the switch when the wire is cold and adapted on passage of current to lengthen and permit the upper end of the arm to move to the first position; d. a conductive rigid arm insulated from the resilient arm, the rigid arm being pivotally attached to the base means at a point spaced above the securement of the resilient arm to the base means and extending upward alongside the resilient arm on the side opposite the resistance wire, the rigid arm being adapted to move in the same direction as the resilient arm; e. contact means electrically integral with and mounted on the arms respectively at a level adjacent their upper ends, the contact means being closed when the resilient arm is in the first and the second positions; f. lost-motion means associated with the two arms and spaced down from the contact means toward the pivot and adapted to permit the resilient arm to move freely away from the first position toward the second position and then to move the rigid arm with the resilient arm so that the contacts separate as the resilient arm leaves the first position and re-engage as the resilient arm closely approaches the second position as the wire cools after the current is interrupted; and g. means electrically connecting one side of a power supply to the lower end of the resistive wire, said one filament to the rigid arm, the said other filament to the resilient arm, and the other side of the power supply directly to the filaments, whereby the resistance of the other filament by itself is sufficient load to maintain the resistive wire at a length when the contacts are disengaged such that the contacts remain disengaged.
 12. A switch as claimed in claim 11 wherein the lost motion means comprise an insulating layer on the resIlient arm and finger means aligned with the layer and disposed on the rigid arm on the said other side of the switch from the layer.
 13. A switch as claimed in claim 11 wherein the switch is disposed inside the glass envelope of an incandescent light bulb. 